The proposed research aims to study the links between family process and maternal adjustment using a genetically-informed design, behavioral genetics analyses and techniques for assessing family process. This study will be the first to use this integrative approach to test any comprehensive model linking family process to mental health. Recent findings from research on family systems will be used, as well as major advances in behavioral genetics, to develop a model linking mother's mental health to (1) her stable psychological attributes such as personality and temperament, (2) to her relationship with her current family including her marriage and relationships with her children and (3) to characteristics of her husband and his relationship with her children. The study will use a population-based sample large enough to provide power adequate for a rigorous test of this model: The Swedish Twin Registry. The study will employ state-of-the-art measures of family process including video recording of mother-child, father-child, and marital interaction in the home setting. The study will be conducted by a team at three sites: George Washington University, Karolinska Institute in Stockholm and Lund University. Analytic models will focus on the delineation (1) of specific individual, heritable traits which elicit variations in parent-child and marital relationships; (2) of how relationships may mediate genetic effects on psychopathology; and (3) of social experiences in each sister's environment which are a unique (nonshared) set of influences on her development.